The present invention relates in general to a coaxial connector. More particularly, the invention pertains to a millimeter wave connector that is particularly adapted for high frequency applications including frequencies above 40 GHz up to and including frequencies even as high as 140 GHz.
At frequencies above 40 GHz, there is no satisfactory coaxial connector that is available, particularly one that permits quick and accurate interconnection of different components or circuit elements using a flexible or semi-rigid cable, such as a standard coaxial cable. The well-known SSMA connector is the smallest acceptable connector available at the present time. The SSMA connector has dimensions which allow energy to propagate in a non-TEM mode at frequencies above 38 GHz. Thus, this connector is generally only effective in use at frequencies up to 38 GHz maximum. The propagation in a non-TEM mode at frequencies above 38 GHz introduces significant reduction in the accuracy and reliability of such a connector when used above this frequency.
In general, in order to operate at higher frequencies, it is necessary to reduce the coaxial conductor dimensions and/or the effective dielectric constant of the dielectric support in the cable. As the coaxial conductor dimensions are reduced, serious mechanical problems of fragility, alignment and tolerances are encountered, which eventually become so severe that the standard coaxial connector approach is no longer effective and has to be abandoned.
The aforementioned series of SSMA coaxial connectors is currently the only coaxial connector series with an associated military specification (MIL-C-39012). In its military standard configuration, it can be used without higher order mode problems as indicated previously, only up to a maximum frequency of 38 GHz. With some minor modifications to the connector, it can be used up to 40 GHz without moding problems. At 40 GHz, the SSMA connector is generally rated for a maximum VSWR of 1.47 at a maximum dissipative loss of 0.25 dB performance which is not acceptable for the measurement accuracy one realistically expects. At higher frequencies not only do the problems of mechanical fragility, alignment, and tolerance become more and more serious, but the VSWR and loss problems are further compounded.
Accordingly, it is an object of the present invention to provide an improved coaxial cable connector particularly usable at millimeter wave frequencies at least in a range from 18 GHz up to 110 GHz.
Another object of the present invention is to provide an improved coaxial connector that can be made very conveniently in relatively small sizes for high frequency applications.
Still another object of the present invention is to provide an improved coaxial cable connector that provides for quick, simple, and accurate connection and disconnection thereof.
Another object of the present invention is to provide an improved millimeter wave coaxial connector that is characterized by improved VSWR and improved dissipative loss, particularly at frequencies above 38 GHz.
Still another object of the present invention is to provide an improved millimeter wave coaxial connector that is a sex-less connector.